1. Technical Field
The invention relates to a multilayer absorbing structure including at least one liquid storage layer, preferably with a liquid reception layer, a liquid storage layer and a liquid distribution layer using cellulose fibers and a super absorbing polymer. The invention also relates to a method and an apparatus for producing the structure.
2. Description of the Background Art
Multilayer absorbing structures using cellulose and super absorbing polymers abbreviated as SAP, e.g. in the form of SAP particles or SAP fibers have been known for many years and are being used as a layer material in disposable products, e.g. in hygiene products, medical products and industrial products.
Fiber layers with absorbent layer in which binder materials are being used for stabilizing the absorbent layer and for avoiding abrasion of the fibers are known. The layers of such layer material include binder materials, e.g. in the form of fibers, powder, hot melt glues, solvent-binder mixes for application in liquid form or similar.
For example EP 1721 036 describes producing a fiber web made of cellulose fibers with absorbing properties through an airlaid method. The fiber web includes several layers. An inner absorbent layer includes a point bonded cellulose material with a super absorber. In order to prevent creating dust from the fibers, called “linting”, which is generated through abrasion or fussing of cellulose fibers, the fibers, in particular in the outer portions of the center fiber web are impregnated with water-latex mix.
When an absorbing structure which includes e.g. a liquid reception layer, a liquid storage layer and a liquid distribution layer is wetted, e.g. by a liquid, the liquid moves from the liquid reception layer to the liquid storage layer through capillary effects. Superfluous liquid can enter from the liquid storage layer into the liquid distribution layer and can be distributed by the liquid distribution layer through pore structure selected accordingly and can be fed back into the storage layer if necessary. This prevents undesirable back wetting effects which can occur through a run out of liquid from a liquid reception layer into a liquid distribution layer and beyond, e.g. onto the skin of a bearer of a hygiene product. However, such products tend to have considerable deficiencies with respect to wearing comfort. Thus, e.g. a liquid storage layer wetted and compressed through liquid absorption and subsequent deformation, this means through regular use, does not tend to go back into its original position after it is unloaded. For example, when SAP particles are loaded with moisture and deformed, a gluing effect between the particles can be created. For known relatively compact liquid storage layers thus the capacity for absorbing additional liquid is substantially reduced which impairs wearing comfort.